Recently, the demand for a lens having a gradient of color density increases as an eyeglass lens having high fashionable properties, and various eyeglasses using lenses having density gradients of various colors are commercially available. Of those commercially available eyeglasses, there is an eyeglass using a lens having a photochromic gradient.
The lens having a photochromic gradient is disclosed, for example, in Japanese patent application (OPI) No. 51412/77. (The term "OPI" as used herein refers to a "published unexamined Japanese patent application".) This lens is a silver halide-based lens having a photochromic gradient which is provided by continuously changing the particle diameter of silver halide particles.
On the other hand, conventional lens having a gradient of color density use only a single color, regardless of an ordinary coloration or photochromic coloration, and the monotonousness in color greatly detracts from the fashionable properties of the lens.